Flower A M, Osborne R S, Silhavy T J
Department of Molecular Biology, Princeton University, NJ 08544.
EMBO J. 1995 Mar 1;14(5):884-93. doi: 10.1002/j.1460-2075.1995.tb07070.x.
The secretion of proteins from the cytoplasm of Escherichia coli requires the interaction of two integral inner membrane components, SecY and SecE. We have devised a genetic approach to probe the molecular nature of the SecY-SecE interaction. Suppressor alleles of secY and secE, termed prlA and prlG, respectively, were analyzed in pair-wise combinations for synthetic phenotypes. From a total of 115 combinations, we found only seven pairs of alleles that exhibit a synthetic defect when present in combination with one another. The phenotypes observed are not the result of additive defects caused by the prl alleles, nor are they the consequence of multiple suppressors functioning within the same strain. In all cases, the synthetic defect is recessive to wild-type secY or secE provided in trans. The recessive nature argues for a defective interaction between the Prl suppressors. The extreme allele specificity and topological coincidence of the mutations represented by these seven pairs of alleles identify domains of interaction between SecY/PrlA and SecE/PrlG.
大肠杆菌细胞质中蛋白质的分泌需要两个内膜整合成分SecY和SecE的相互作用。我们设计了一种遗传学方法来探究SecY - SecE相互作用的分子本质。分别称为prlA和prlG的secY和secE的抑制等位基因，以成对组合的方式分析其合成表型。在总共115种组合中，我们仅发现七对等位基因，当它们相互组合时会表现出合成缺陷。观察到的表型既不是由prl等位基因引起的累加缺陷的结果，也不是同一菌株中多个抑制子发挥作用的结果。在所有情况下，合成缺陷对于反式提供的野生型secY或secE是隐性的。隐性性质表明Prl抑制子之间存在缺陷性相互作用。这七对等位基因所代表的突变的极端等位基因特异性和拓扑一致性确定了SecY/PrlA和SecE/PrlG之间的相互作用结构域。
